Conventionally, there is an image generation device that synthesizes an overview image provided by overviewing an environment of a vehicle, based on a camera image of the vehicle. An image generation device superimposes an image that indicates a three-dimensional shape of a vehicle, at a position of a road surface where the vehicle exists thereon, on an overview image, so that the vehicle is displayed virtually (see, for example, Japanese Laid-open Patent Publication No. 2016-192772).
However, in a case where a vehicle is indicated by a three-dimensional shape thereof like a conventional technique, it may be difficult for a driver of the vehicle to recognize a vehicle width in an overview image, depending on a position of a virtual viewpoint.